As I write this, the latest episode of Doctor Who, “Angels Take Manhattan”, has now aired not only in its home country of Britain, but in the US and also on Australian TV. If you haven’t seen it yet and are intending to, stop reading. There May Be Spoilers.

That said, I would say it was a good episode. The most important thing that happened in it was that it was the last episode for The Doctor’s companions Amy and Rory. At least on that point it sorted out how they would leave The Doctor in a reasonably original way. But there was really no other way to do it.

One of the problems with the ongoing story of The Dcotor is how do you migrate companions? They almost inevitably find adventuring with him far more interesting, far more exciting and far more rewarding than whatever life they left. It is a challenge for the writers to find not just a good reason for a companion to leave, but a really good, and above all credible reason for them to leave. I mean, what can be better than travelling in all of time and space with a Time Lord?

Way back in the original series, the first companion to be jettisoned, Susan, was actually deliberately left behind by The Doctor. She was not impressed, to put it mildly. In the most recent two series the issue of how companions leave has been raised as an actual conversation topic several times. Characteristically, The Doctor doesn’t like to talk about it and this has been lampshaded several times, too. It is also a nice “writerly” way of limiting exploration of the topic. But this can only be put off so many times and in “The Power of Three”, Amy and Rory’s second last adventure, Rory’s father manages to corner The Doctor about it. That’s where he is forced to admit that sometimes they die.

It is a challenge as a writer coming up with some plausible event that would terminate a companion’s adventures with The Doctor. None of the characters want this to happen; it must usually be enforced by the story. The stranding of Rose Tyler in an alternative dimension away from The Doctor was both spectacular and heart-wrenching. But it had to be written. And it had to be a forced separation. The writers had to put Rose through the wringer and leave her on the other side of it away from The Doctor.

Much the same thing happened with Amy and Rory. The Doctor had a realization way back in “The God Complex” that his very way of living regularly puts his companions in danger. Too much danger: he has to leave them and let them live their own boring lives before he gets them killed. He does so for Amy and Rory, but it turns out that he can’t quite leave these two alone. This is a theme in the most recent series. It eventually takes the most recent episode, “Angels Take Manhattan”, to forcibly remove Amy and Rory from The Doctor’s companionship, to a place in time and space where he can no longer go. In fact, the whole point of the episode is to simply do that to them.

Once again, the writers- in this case, Steven Moffat – have to put their characters through the wringer. Again. It helps that the viewer will probably be emotionally invested in them. That is a given. (Then, too, fans know this will be Amy and Rory’s last episode.)

A writer must not be afraid to do dastardly things to their characters. In a clinically dispassionate view of writing, you must make your audience fall in love with your character and then give them something impossible to overcome or choose between. Whether they succeed or not depends on what you want your readers to feel but the journey to get there is the story you’re writing. And remember that oft-times the success is partial or compromised: they may only be able to succeed by failing. Amy and Rory got to live their lives out together: but without any way for The Doctor to visit them again. Very bittersweet. It was a kind of heroic sacrifice. And their choices should confirm what the reader already knows or guesses about their character.